This seaplane version of the 03U-3 was identical to the landplane version except for installation of pontoons and a float.  This model was an upgraded 03U-2, the major change being use of the latest Pratt & Whitney R-1340-12 engine.  The first 28 of these aircraft were convertible types for land and sea operation.  This was the first Vought aircraft to utilize Vought-designed pontoon and floats.  Prior to this time the Navy purchased them from other sources and attached them to the aircraft themselves.  This was also the first aircraft to be equipped for cast-type recovery by the ships.

Their service itinerary was similar to that described for the O3U-1.  Some were still stationed at various Naval Air Stations as late as 1941.